The present invention relates generally to rotary drive anti-overtravel devices and more particularly to a new and improved rotary drive anti-overtravel device having notable application with a rotary counter drive train for preventing inertia and/or manual overtravel of the rotary counter and resulting count inaccuracy at the end of a count.
The conventional mechanical computer employed in gasoline dispensing apparatus incorporates a mechanical register having a pair of rotary counters on each of two opposite faces of the register for registering, on each of the two opposite faces, the cost and volume amounts of fuel delivered. Such a register is shown and described in U.S. Pat. No. 2,814,444 of Harvey N. Bliss, dated Nov. 26, 1957 and entitled "Register". The gasoline pump computer also conventionally incorporates a mechanical price variator of the type shown and described in U.S. Pat. No. 3,413,867 of Richard B. Hamlin, dated Dec. 3, 1968 and entitled "Variator", for establishing and posting the unit volume price of fuel. The variator has a center shaft connected for being mechanically driven by a gasoline meter, and the variator center shaft is connected for driving the volume counters of the register for registering the volume amount of fuel delivered. The price variator has settable gearing for establishing the unit volume price of fuel, and the output of the settable gearing is connected for driving the cost counters of the register for registering the cost amount of fuel delivered in accordance with the volume amount of fuel delivered and the unit volume price established by the setting of the variator gearing.
Because of the rapidly increasing price of gasoline and the concomitant higher drive ratio setting of the variator gearing, the cost counters are rotated at a substantially higher rate for any given volume rate of delivery of gasoline and whereby inertia overtravel of the high speed cost counters, resulting in an inaccurately high cost counter reading, is increasingly more likely to occur at the end of a fuel delivery.
In the past, anti-backlash devices (of the type shown and described in Pilz et al. U.S. Pat. No. 3,251,544, dated May 17, 1966 and entitled "Gear Train Control Arrangement" and in Smilgys U.S. Pat. No. 3,847,347, dated Nov. 12, 1974 and entitled "Rotary Drive Anti-Backlash Device") have been employed in the cost and volume counter drive trains of a fuel pump register for biasing the rotary drive trains in the reverse angular direction and thereby for resisting inertia overtravel of the drive trains and/or removing any overtravel if it occurs. However, the reverse bias provided by such anti-backlash devices adds a significant and undesirable additional load and whereby such anti-backlash devices have significant disadvantages in some fuel pump applications and in other applications where the resultant required drive torque is excessive.